Use non-null DateFormat for CustomDateEditor in tests

Closes gh-29419

spring-beans/src/test/java/org/springframework/beans/propertyeditors/CustomEditorTests.java

@@ -722,7 +722,7 @@ class CustomEditorTests {
 
 	@Test
 	void testCustomDateEditor() {
-		CustomDateEditor editor = new CustomDateEditor(null, false);
+		CustomDateEditor editor = new CustomDateEditor(new SimpleDateFormat("MM/dd/yyyy"), false);
 		editor.setValue(null);
 		assertThat(editor.getValue()).isNull();
 		assertThat(editor.getAsText()).isEmpty();
@@ -730,7 +730,7 @@ class CustomEditorTests {
 
 	@Test
 	void testCustomDateEditorWithEmptyAsNull() {
-		CustomDateEditor editor = new CustomDateEditor(null, true);
+		CustomDateEditor editor = new CustomDateEditor(new SimpleDateFormat("MM/dd/yyyy"), true);
 		editor.setValue(null);
 		assertThat(editor.getValue()).isNull();
 		assertThat(editor.getAsText()).isEmpty();